@_ado: Sublime will open a newwindow when started if -n or --new-window is included on the command line. Maybe you have that set somewhere. Look at the icon or shortcut you use to start Sublime and see if any parameters are specified.

As iamntz mentioned, this may also be affected by the settings remember_open_files, hot_exit, and open_files_in_new_window if on OSX.

Those are just the defaults - I haven't changed those. Here's the testing I've done in Windows:

1. Close Sublime with no documents open, open sublime, no new file created.2. Close Sublime with new file open (not saved to disk), open sublime, same new file exists, but no other tabs3. Close Sublime with file open (real file on disk), open sublime, same file opens but no other tabs4. Close Sublime with no documents open, open text file with Sublime using context menu, Sublime opens that file, no other tabs

HOWEVER... there is a default blank slate that Sublime opens with. The text editor is there and available, but no tabs are created. If you start typing, then a tab is created. To me this is awesome. I don't have to specifically create a new file. It's ready for me to type - or not type. If I open a file, there's no New document tab created or anything. Is that what you're seeing?